The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find resources to help them understand and teach evolution. The resources are organized into different learning paths for example "What does T. rex look like?"
Charles Darwin's theory of natural selection explains how over time creatures that are better able to adapt biologically to changing environments survive and those that are not extinct. Science is all about the process of biological evolution.
What is Evolution?
The word evolution can have many nonscientific meanings. For example it could mean "progress" and "descent with modifications." It is scientifically based and is used to describe the process of change of characteristics over time in organisms or species. In terms of biology this change is based on natural selection and genetic drift.
Evolution is a central tenet of modern biology. It is a concept that has been tested and proven through thousands of scientific tests. It does not address spiritual beliefs or God's presence like other theories in science, like the Copernican or germ theory of diseases.
Early evolutionists such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to evolve in a gradual manner over time. This was called the "Ladder of Nature" or scala Naturae. Charles Lyell used the term to describe this idea in his Principles of Geology, first published in 1833.
In the early 1800s, Darwin formulated his theory of evolution and published it in his book On the Origin of Species. It asserts that different species of organisms share an ancestry that can be traced through fossils and other lines of evidence. This is the current perspective on evolution, which is supported in many scientific fields which include molecular biology.
Scientists aren't sure how organisms evolved, but they are confident that natural selection and genetic drift is responsible for the evolution of life. People with desirable traits are more likely than others to survive and reproduce. These individuals pass on their genes to the next generation. Over time, the gene pool gradually changes and develops into new species.
Certain scientists also use the term"evolution" to refer to large-scale changes in evolutionary processes like the creation of a new species from an ancestral species. Other scientists, like population geneticists, define the term "evolution" more broadly, referring to the net change in allele frequencies over generations. Both definitions are accurate and palatable, but some scientists believe that allele-frequency definitions do not include important aspects of evolution.
Origins of Life
One of the most crucial steps in evolution is the appearance of life. The beginning of life takes place when living systems begin to evolve at a micro scale, for instance within cells.
The origins of life is one of the major topics in various disciplines such as geology, chemistry, biology and chemistry. The nature of life is an area of great interest in science, as it challenges the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."
Traditionally, the belief that life could emerge from nonliving things is known as spontaneous generation or "spontaneous evolution." This was a popular belief prior to Louis Pasteur's experiments proved that it was impossible for the emergence of life to occur by the natural process.
Many scientists believe that it is possible to transition from nonliving substances to life. The conditions necessary for the creation of life are difficult to replicate in a laboratory. This is why researchers studying the origins of life are also interested in determining the physical properties of early Earth and other planets.
Furthermore, the growth of life depends on the sequence of extremely complex chemical reactions that can't be predicted based on basic physical laws alone. This includes the conversion of long information-rich molecules (DNA or RNA) into proteins that perform a function as well as the replication of these complex molecules to generate new DNA or sequences of RNA. These chemical reactions can be compared with a chicken-and egg problem: the emergence and development of DNA/RNA, a protein-based cell machinery, is essential for the onset life. However without life, the chemistry required to make it possible does appear to work.
Abiogenesis research requires collaboration among scientists from various disciplines. This includes prebiotic chemists, planet scientists, astrobiologists geophysicists, geologists, and geophysicists.
Evolutionary Changes
The term "evolution" today is used to describe cumulative changes in genetic characteristics over time. These changes can be the result of adapting to environmental pressures, as explained in Darwinism.
This mechanism also increases the number of genes that provide an advantage for survival in a species, resulting in an overall change in the appearance of a group. These evolutionary changes are triggered by mutations, reshuffling of genes during sexual reproduction, and gene flow.
While mutation and reshuffling of genes happen in all organisms and the process by which beneficial mutations become more common is known as natural selection. As noted above, individuals with the beneficial trait have a higher reproduction rate than those that do not. This difference in the number of offspring that are produced over a long period of time can result in a gradual change in the average number of beneficial traits within a group.
A good example of this is the increase in the size of the beaks on different species of finches found on the Galapagos Islands, which have evolved different shaped beaks to allow them to more easily access food in their new habitat. These changes in shape and form can aid in the creation of new organisms.
The majority of changes are caused by a single mutation, although sometimes multiple occur simultaneously. The majority of these changes are neither harmful nor even detrimental to the organism, however, a small proportion of them can have an advantageous impact on the longevity and reproduction of the species, thus increasing the frequency of these changes in the population over time. Natural selection is a mechanism that can produce the accumulating changes over time that lead to the creation of a new species.
Some people confuse the idea of evolution with the notion that inherited characteristics can be altered through conscious choice or use and abuse, a concept called soft inheritance. This is a misunderstood understanding of the nature of evolution, and of the actual biological processes that trigger it. A more precise description is that evolution is a two-step procedure that involves the distinct, and often competing, forces of natural selection and mutation.
Origins of Humans
Modern humans (Homo sapiens) evolved from primates - a group of mammals that also includes chimpanzees, gorillas, and bonobos. The earliest human fossils show that our ancestors were bipeds. They were walkers on two legs. Genetic and biological similarities suggest that we are closely related to chimpanzees. In reality we are the most closely with chimpanzees in the Pan genus that includes pygmy and bonobos and pygmy-chimpanzees. just click the following document shared between modern humans and chimpanzees was between 8 and 6 million years old.
Humans have evolved a variety of traits over time, including bipedalism, the use of fire and advanced tools. It's only in the last 100,000 years that we've developed the majority of our important characteristics. These include language, large brain, the capacity to build and use sophisticated tools, and a the diversity of our culture.
Evolution happens when genetic changes allow members of a population to better adapt to their surroundings. Natural selection is the process that drives this change. Certain traits are preferred over others. The more adaptable are more likely to pass on their genes to the next generation. This is how all species evolve and is the basis of the theory of evolution.
Scientists call this the "law of natural selection." The law states species that have an ancestor in common will tend to acquire similar traits as time passes. This is because the traits allow them to survive and reproduce in their natural environment.
All organisms possess an molecule called DNA that holds the information needed to guide their growth. The structure of DNA is composed of base pairs that are arranged in a spiral around phosphate and sugar molecules. The sequence of bases within each strand determines the phenotype, the characteristic appearance and behavior of an individual. Different mutations and reshuffling of the genetic material (known as alleles) during sexual reproduction cause variations in a population.
Fossils of the earliest human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. While there are some differences between them they all support the hypothesis that modern humans first came into existence in Africa. Genetic and fossil evidence also suggest that early humans moved from Africa into Asia and then Europe.